Re: [Boost-users] [ptr_container] Pair type for boost::ptr_map?

From: Nat Goodspeed (nat_at_[hidden])
Date: 2008-04-18 15:14:34

Robert Dailey wrote:

> I have the following code:
> 
> void HandlePair( std::pair<int, char*>& mypair )
> {
> }
> 
> void main()
> {
>         boost::ptr_map<int, char> mymap;
>         HandlePair( *mymap.begin() );
> }
> 
> 
> What's the proper way to accept pairs in the HandlePair function? 

I'd suggest basing it on your actual ptr_map type, e.g.:
void HandlePair(const boost::ptr_map<int, char>::value_type& mypair) {}

I usually use map_type::value_type (using an appropriate typedef for 
map_type) even when working with std::map, since the type of a pair 
stored in a std::map<A, B> is NOT the same as std::pair<A, B>: it's 
actually std::pair<const A, B>. I have no idea what the transformation 
is for boost::ptr_map, but in any case, its value_type should give you 
what you want.